Study On In-situ Preparation And Properties Of Nylon6/Inorganic Nanocomposites

Polymer include Nylon gained rapid development and wide application in contemporary society with its advantages of light weight, high strength and good processability. However, with the development of society, traditional polymer can no longer meet the higher and higher requirement of performance and application scope. And developing new high-performance polymer become more difficult and will cost very much. So, to improve the performance through polymer modification becomes necessary. The emergence and development of nanometer materials start another way to polymer modification. In this paper, we choose nanoSiO₂ and nano-Al2O3, which are cheap and have reached large-scale industrial production, to prepared nylon 6 / inorganic nanocomposite,The main content and conclusions of this paper are as follows:In this paper, Nano powder was dispersed in the caprolactam melt before polymerization, and then nylon 6/nano-SiO₂ and nylon 6/nano-Al2O3 composites were prepared by in-situ polymerization. In order to develop a suitable way of preparation of Nylon6/nano-SiO₂ and nylon 6/nano-Al2O3 composites, the synthesis of composites was carried out in factory, according to the process of industrialization. Meanwhile, through the injection molding machine and melt spinning machine to research the processability, it showed that composites still have excellent processing performance. The dispersion of nano powder and interfacial bonding were observed by scanning electron microscopy（SEM）, it showed that nano powder can be evenly dispersed in nylon 6, and the interfacial bonding was strong.Analyzed thermal properties of the nylon 6, nylon 6/nano-SiO₂ and nylon 6/ nano-Al2O3 by thermo gravimetric analyzer（TGA） and differential scanning calorimeter（DSC）,the results showed that the two inorganic nano materials have little effect on the thermal stability of nylon 6 because of the connection are mainly hydrogen bonds between them, but the melting behavior of composite materials have a significant change and there was a lower melt peak appeared—— crystallization behavior changed. There are heterogeneous nucleation and steric hindrance with adding nano-SiO₂ and nano-Al2O3, it would impact on the degree of perfection 、crystallization rate、crystallization temperature and grain size of of nylon 6 by DSC and polarizing microscope, it would have interactions when add different types and quantity presents of the two nanoparticles. Capillary rheometer analysis showed that there is a thickening effect on the rheological behavior of nylon 6, the two kinds of nanoparticles can increase a little apparent shear viscosity of nylon 6,but the effect is not obvious.We evaluated the properties,contrasted the reinforced and toughening effect of nano-SiO₂ and nano-Al2O3 for nylon 6 by testing tensile strength and notched impact strength of injection molding and single fiber, respectively, we confirmed the addition and investigated the toughening mechanism by comparing the property of nylon 6 /nano-SiO₂ and nylon 6/nanoAl2O3 composites, The results showed that both nano-SiO₂ and nano-Al2O3 can toughen nylon 6, but the best dosage are different; the sensitivity of composite fiber for nano powder was higher than plastic, it showed significant adverse effects when too much nano powder was added.